Hereinafter, the structure of a wireless communication system and the assignment (or allocation) method of a radio channel, which are generally used, will be briefly described.
FIG. 1 illustrates a conceptual view of a communication system using at least one or more radio frequencies (RFs).
Referring to FIG. 1, a communication system supporting radio frequencies (RFs) may configure a communication system by using a total of N number of RFs. A BS (Base Station) may use one or more RFs so as to simultaneously transmit data to a single user equipment. And, similarly, a user equipment may also use one or more RFs so as to simultaneously transmit data to the base station. At this point, one RF may be configured by using each single Physical Channel or by using multiple physical channels. And, the base station and the user equipment may be provided with a plurality of transmission antennas (Tx). Such system may also be referred to as a multiple carrier system.
FIG. 2 illustrates exemplary structures of a transmitter and a receiver using multiple radio frequencies.
Referring to FIG. 2, the logical concept of a physical channel may be known by using an uplink channel and a downlink channel. In FIG. 2, N number of a radio frequencies may be configured (RF 1, RF 2, . . . , RF N), M number of physical channels may be configured (PHY 1, PHY 2, . . . , PHY M).
Signals that are generated from the transmitter through N number of RFs may be transmitted to a receiving end through M number of physical channels. At this point, the N number of signals may be scheduled to be simultaneously transmitted through an RF Multiplexer. The signals that are multiplexed through the RF multiplexer are transmitted from the transmitter to the receiver through Nt number of physical transmission antennas (Tx).
The signals, which are transmitted as described above, may be received through Nr number of receiving antennas (Rx) of a receiver, which supports Multi-RF reception through a radio channel. The signals that are received through Nr number of reception antennas may be divided to M number of PHY channels through a Multiple RF Demultiplexer. The receiver may recover the signals that are transmitted from the transmitter through each of the divided PHY channels.
In each physical channel of the multi-RF transmitter and receiver, all methods being used in a system using the conventional single RF may be used. In configuring the system shown in FIG. 2, multiple RF communication modules may be configured, and a single RF module may be used, so as to sequentially generate and recover singles of multiple physical channels.
In case of using multiple RFs, a multiple antennas method or a control channel should be designed based upon the channel characteristics of each frequency. Unlike the case of using a single RF, when using multiple RFs, the channel characteristic for each RF may vary. Accordingly, by designing the multi-antenna method and control channel based upon the channel characteristic of each frequency, the system may be optimized. Additionally, among the multiple carriers, when some of the carriers are configured to have the same frame structure as a specific conventional system, the carrier is required to be configured so that the user equipment designed for the conventional system and the user equipment designed for the new system can both be operated.